Different designs of hybrid drives for cycles are known, including those of arranging an electric motor directly on the rotational axis of the rear wheel, the front wheel or the crank shaft. Arrangements integrated in this way require specially adapted and therefore complicated and expensive motor designs which are also subject to integration-related restrictions. Designs in which the electric motor is supported on the cycle frame in the vicinity of the crank housing, directly on or separately from the crank housing, and drives the rear wheel either separately from the crank via a coupling of its own or via a coupling in common with the crank, have therefore prevailed in the market. Reference is made for example to U.S. Pat. No. 4,541,500 B and U.S. Pat. No. 5,242,335 B. Such an arrangement does enable conventional motors to be used and also enables the performance of the crank drive and the electric drive, which is different in terms of rotational speed and torque, to be flexibly adapted; conversely, only a limited design space is however available around the bottom bracket housing, and assembly, maintenance and repair prove difficult. Arranging the motor between the bottom bracket housing and the rear wheel, as disclosed for example in U.S. Pat. No. 4,541,500 B, requires electric motors which are narrow in diameter and exhibit a small nominal torque and correspondingly high nominal rotational speed. The rotational speed of the motor is geared down onto the rear wheel pinion via a multiple-stage reducing gear system. If larger motors with correspondingly larger torque are to be used, the distance between the wheel axes has to be increased, in order to create sufficient space between the bottom bracket housing and the rear wheel. As a result, the known hybrid designs all require drastic changes to the conventional cycle geometry, up to and including a complete re-design.